1,2-dinitro-tetrachlorobenzene as a microbicidal wood preservative



United States Patent 3,536,815 1,2-DINITRO-TETRACHLOROBENZENE AS A MICROBICIDAL WOOD PRESERVATIVE Walter Traber, Riehen, Switzerland, assignor to Geigy Chemical Corporation, Ardsley, N.Y., a corporation of New York No Drawing. Filed Jan. 19, 1967, Ser. No. 610,243 Claims priority, applicafi9osn7/s6vgitzerland, Jan. 25, 1966, .Int. Cl. A01n 9/20 US. Cl. 424-349 Claims ABSTRACT OF THE DISCLOSURE "ice preservation of wood. Wood impregnated with this active substance is not injured or coloured and overlacquering with colours and lacquers is not hindered. 1,2-dinitrotetrachlorobenzene easily penetrates into the wood and, because of its low steam pressure, has a more protracted action than, for example, pentachlorophenol. In contrast to most of the active substances used in wood preservation, 1,2-dinitro-tetrachlorobenzene has no smell and is not toxic.

Tests with different bacteria and fungi strains showed that of the three isomeric dinitro-tetrachlorobenzenes, only 1,2-dinitro-tetrachlorobenzene has good bactericidal and fungicidal properties.

The action on bacteria was tested on the following strains of bacteria: Staphylococcus aureus SG 511, Escherichia coli NCTC 8196, Bacillus pumilus, Sarcina ureae, Pseudomonas pyocyanea.

The Agar incorporation test according to Leonard and Blackford was used as test method: Nutrient agar plates having 300, 100, and 3 p.p.m. active substance (ppm. means parts of active substance per 10 parts of diluent) are inoculated with solutions of the strains given above and incubated 2X 24 hours at 37 C. The marginal concentrations which inhibit the growth of the individual strains are shown in the following table:

Staph. E. 0011' Bus. Sar. Pseud Compound SG 511 8196 has cyanea 1,2-dinitro-tetrachlorobenzene 30 30 3 30 30 1,3-dinitro-tetracl1lorobenzene (comparative substance) 300 300 300 300 300 1,4-di nitro tetrachlorobenzene (comparative substance) 300 300 300 300 300 The present invention concerns new microbicidal wood The action on fungi was tested on the following strains preservative agents which in addition reduce the comof fungi: Aspergillus niger,Penicilliumitalicum,Fusarium bustibility of the wood and which contain a nitrated chlorobenzene derivative as active substance, also methods for combatting microorganisms which injure and destroy wood, and for the protection of wood and wooden objects using this active substance and agents containing it, as well as the wooden materials and objects protected thereby.

1,2-dinitro-tetrachlorobenzene has become known from Pen. Fus. Cami.

Asp. italioryalbi- Acr.

Compound migcr cum sporum cans spec.

1,Q-dinitro-tetraehlorobenz ene 30 3 30 3 3 1,3-dinitro-tetrachlorobenzeue (comparative substance) 300 300 300 300 300 1, l-dinitro-tetrachlorobenzene (comparative substance) 300 300 300 300 300 US. Pat. No. 1,947,926 as seed dressing and from Belgian Pat. No. 639,474 as an intermediate product for the synthesis of tetrachloro-o-phenylenediamines. Two isomers of said compound, namely, 1,3-dinitroand 1,4-dinitro-tetrachlorobenzene have been described in French Pat. No. 963,460 as bacten'cidally active ingredients.

It has now been found that 1,Z-dinitro-tetrachlorobenzene which shows an excellent microbicidal action against micro-organisms which injure and destroy wood, is also capable of reducing the combustibility of wood, and is therefore excellently suitable for the protection of wood and wooden objects from attack by fungi and bacteria which destroy and injure wood. The microbicidal activity of 1,Z-dinitro-tetrachlorobenzene is superior to its 1,3- and 1,4-dinitro isomers.

The active substance is colourless, stable under the application conditions and of low vapor pressure. These properties make it particularly valuable for use in the To determine the action on micro-organisms which decompose cellulose and lignin, various types of wood were impregnated in different ways with 1,2-dinitro-tetrachlorobenzene and then infected with soft rot and with blue stain (Pullularia pullulans).

PROTECTIVE ACTION AGAINST SOFT ROT Blocks of beech and pine sap wood (20 x 10 x 5 mm. in size) were dried for 14 hours at C. and then weighed to determine their dry weight. The Wood samples are then soaked for 24 hours at room temperature under normal pressure with a 2.5 and a 1% acetone solution of the active substance and then stored for one week at room temperature under normal .pressure. Afterwards, the two thirds of the length of the wood samples were buried in the earth, the remaining one-third being left above the surface. The beech samples were then left for 3 months and the pine samples for 6 months in the earth which had a water content of 2535%, a temperature of 28 C. and 70-80% relative humidity. The samples of Wood were then washed with a soft brush under flowing water and afterwards dried for 14 hours at 105 C. whereupon they were Weighed. Compared with the weight found before the test, the wood samples had lost weight. The amount of weight lost shows to what extent the wood is protected by the active substances against soft rot (micro-organisms which decompose cellulose and lignin).

The losses in weight of the wood samples treated with active substances expressed in percent, can be seen from the following table:

tion of active substance on all sides, the treatment being such that the amount applied is, in all, 200 g. of solution per sq. m. (10 g. of active substance per sq. m.). The rods are then dried for 4 weeks at 20 and 40% relative humidity until the weight is constant.

The dried, prepared rods are then hung in the centre of a vertical fire tube and subjected to a 10 cm. long flame from a bunsen burner for 3 mintues. The amounts burnt in percentage of the weight of the rod both on exposure to the flame and after removal of the flame are determined by constant control of the weight and the duration of burning after removal of the flame is measured.

Loss in Weight in percent Cone. of act. subs.

in acetone solu- Compound tions, percent 1,2-dinitro-tetrachlrobenzene Pentachlorophenol (comparative substance) From the values given in the table, it can be seen that 1,2-dinitro-tetrachlorobenzene has a better protective ac- The results given in the following table are the average values obtained from tests.

Amount burnt in percent of initial weight after a test time in minutes Exposure to flame After flame removal Compound 1' 2' 3' 4' 5' 6 7'.

1,z-dinitro-tetrachlorobenzene 3 10 21 30 32 Pentachlorophenol (comparative substa ce) 11 39 56 e7 73 76 Untreated 5 14 29 42 51 65 56 tion for beech and pine wood against soft rot than pentachlorophenol.

ADDITIVE TO PAINTS TO INHIBIT BLUE STAIN The tests were made according to H. Butin Holz als Rohund Werkstoif 19, (1961) p. 195.

A dispersion colour with a white pigment was used as paint. This colour has a solid content of about 50% and a foundation of copolymeric polyvinyl acetate as binder. The active substance is dissolved in dimethyl formamide/ ethylene glycol monomethyl ether (1:1). This so-called stock solution is so added to the dispersion colour that the dispersion colour to be painted contains 3% of active substance. The colour is applied to pine wood blocks of 20 sq. cm. size (4 x 5 cm.) with a brush. The amount of colour painted on each block was about 170 mg. The treated wood blocks were exposed to open air weather conditions whereby the treated surfaces are directed at an angle of 45 towards the south. After 12 months, the wood blocks were sterilised with ethylene oxide for 1 hour at 55 C. under 5.5 atm. pressure. The blocks were then placed in Kolle flasks on filter paper and inoculated with about 30 cc. of a Pullularia pullulans suspension (blue stain suspension). The flasks were then incubated 12 weeks at 24 C. and 85% relative air humidity. At the end of this time, no change in colour was determined on the surface of the wood blocks which have been painted with dispersion colour containing 1,2-dinitro-tetrachlorobenzene, i.e. 100% protection was given by the coating with the paint containing 1,2-dinitro-tetrachlorobenzene.

As a comparison, pentachlorophenol was incorporated into the dispersion colour in the same way and painted onto blocks of wood of the same size which were exposed at the same time to open air weathering. After sterilisation, inoculation and incubation, black and grey discolourations due to blue stain are clearly visible on these blocks.

RESISTANCE TO FIRE Five pine rods (500 x 20 x 10 mm. in size) having rough edges are each given two applications of a 5% solu- It can be seen from the above results that wood treated with 1,2-dinitro-tetrachlorobenzene burns more slowly and for less time after exposure to fire than the known pentachlorophenol which promotes combustibility both with and after exposure to fire.

1,2-dinitro-tetrachlorobenzene is used in the form of solutions or emulsions for the protection of material and, in particular, of wood. Wood and wooden objects are either impregnated, coated, dipped or sprayed with such liquid agents. The treatment can be given externally or by the technical processes known for the impregnation of wood.

To produce solutions, in particular organic solvents which are substantially without smell and non volatile are used such as mineral oil fractions, tar oils, high boiling aliphatic and aromatic hydrocarbons as well as their chlorinated derivatives. These are used alone or mixed together. Those solvents are preferred which in themselves have an insecticidal action.

To produce emulsion concentrates, organic solvents, dispersing agents and water are used. Examples of solvents are aromatic hydrocarbons as well as the solvents given above. The following substances can be used as dispersing agents: polyethylene glycol ethers of monoand dialkylphenols having 5-15 ethylene oxide radicals per molecule and 8-9 carbon atoms in the alkyl radical, e.g. the products Triton, Tergitol and Igepal, fatty alcohol polyethylene glycol ethers having 5-20 ethylene oxide radicals per molecule and 8 to 18 carbon atoms in the fatty alcohol moiety, e.g. the products Genapol, condensation products of ethylene oxide/ propylene oxide, e.g. the products Pluronics, also alkylaryl sulphonates, alkali and alkaline earth metal salts of di-butyl naphthalene sulphonic acid, fatty alcohol suphates such as salts of sulphated hexadecanols, heptadecanols, octadecanols, octadecenols, and salts of sulphated fatty alcohol polyglycol ethers, e.g. the products Eriopon, amino-fatty alcohol sulphates, e.g. the products Duponol, the sodium salt of oleoyl ethionate, the sodium salt of oleoyl methyl tauride, e.g. the products Akropon, ditertiary acetylene glycols, e.g. the products Surfynol and dialkyl dilauryl ammonium chloride, e.g. the products Aliquat.

In general, the solutions and emulsion concentrates contain the active substance in a concentration between 1 and 80% preferably the content of active substance in the solutions used lies between 4 and 10%. Such solutions can be used direct for the impregnation, spraying or painting of wood and wooden articles. The emulsion concentrates are applied by diluting with water to form emulsions having a content of active substance of 415%- Also other biocidal active substances can be admixed with the agents described according to the invention. Thus, in addition to 1,2-dinitro-tetrachlorobenzene, the new agents can contain, e.g. insecticides such as DDT active substance, other fungicides, bactericides, fungistatics and bacteriostatics, to widen the range of action.

1,2-dinitro-tetrachlorobenzene can be produced according to the Belgian Pat. No. 639,474 by chlorinating 2,4,5- trichloro-nitrobenzene in the presence of chlorosulphonic acid and iodine to form tetrachloronitrobcnzene and then nitrating the latter.

The following non-limitative examples illustrate the production of a few typical forms for application of the agents according to the invention. Parts and percentages are given therein by weight.

EMULSION CONCENTRATE The following substances are used to produce an 8% emulsion concentrate:

8 parts of 1,2-dinitro-tetrachlorobenzene 7 parts of DDT active substance 80 parts of xylene parts of a mixture of emulsifying agents consisting of nonylphenol polyethylene and dodecylbenzene sul phonic acid calcium salt.

The active substance is intimately mixed with DDT active substance and, with the addition of the mixture of emulsifying agents, dissolved in xylene. An emulsion concentrate is obtained which can be diluted with water to any concentration desired. Wood or wooden articles, particularly construction wood can be painted, impregnated or sprayed with such aqueous emulsions.

SOLUTION The following substances are used to produce a 4% solution: 4 parts of 1,Z-dinitro-tetrachlorobenzene 3 parts of DDT active substance 6 93 parts of solvent having a content of aromatic substances of 93%, boiling within 212273, specific weight 0.930.

The active substance and the DDT active substance are dissolved. The solution obtained can be used direct for the impregnation, painting or spraying of wood and wooden articles.

I claim:

1. A method for combatting microorganisms selected from the group consisting of fungi and bacteria which injure and destroy wood and for protecting wood and wooden articles from attack by said microorganisms, which comprises applying to a site of wood or a wooden article susceptible to attack by said microorganisms a microbicidally effective amount of 1,2-dinitro-tetrachlorobenzene.

2. A method as defined in claim 1 in which the 1,2- dinitro-tetrachlorobenzene is contained in a composition having a non-volatile organic solvent and the l,2-dinitrotetrachlorobenzene is present in said solvent in a concentration of from 4 to 10%.

3. A method as defined in claim 1 wherein the compound is contained in an emulsion comprising an organic solvent, water, and a dispersing agent, and the 1,2-dinitrotetrachlorobenzene is present in said emulsion in a concentration of from 4 to 15%.

4. A method as defined in claim 3 in which the solvent is selected from the group consisting of high boiling aliphatic and aromatic hydrocarbons, chlorinated derivatives of said hydrocarbons, dimethyl formamide and ethylene glycol monomethyl ether, and in which the dispersing agent is present in sufiicient amount to maintain the 1,2-dinitro-tetrachlorobenzene emulsified therein.

5. A method as defined in claim 2 in which the solvent is selected from the group consisting of high boiling aliphatic and aromatic hydrocarbons, chlorinated derivatives of said hydrocarbons, dimethylformamide and ethylene glycol monomethyl ether.

References Cited UNITED STATES PATENTS 1,947,962 2/ 1934 Steindorfif l6738 2,786,795 3/1957 Ligett et a1 167-38.6 3,166,594 1/1965 Harris et a1 260-580 ALBERT T. MEYERS, Primary Examiner V. D. TURNER, Assistant Examiner 

